The cleaning of contaminated surfaces, in particular vertical, smooth surfaces in the meat and food processing industry, is relatively difficult. It is not always possible to ensure that the cleaning solution used has a sufficiently long contact time with the soiled surface in the time available. The cleaning solution runs off too quickly without the cleaning effect having been fully utilized.
It has therefore been attempted to clean, in particular, vertical walls using appropriate high-viscosity cleaning compositions. This contacting and the subsequent removal is, however, technically difficult to bring about and is very time consuming. Furthermore, relatively concentrated solutions are used. The use of polymeric thickeners in surfactant cleaning systems is also known. For example, EP-A-O-314 232 describes an alkaline cleaner having thickening properties following dilution to the working solution. To reduce the viscosity in the concentrate, the formulations are mixed with alcohols, such as ethanol or isopropanol, or other solvents which then lose their dilution effect in the working solution; as a result, the viscosity of the working solution to be applied to the surface is increased. The use of these solvents is associated with a considerable ignition and fire hazard because of their low flashpoints.
Furthermore, U.S. Pat. No. 4,438,024 discloses stable aqueous detergent compositions which comprise an amine oxide, a hydrotrope, oleic acid, a complexing agent, water and an alkali metal hydroxide solution for adjusting the pH. They are used in detergent preparations.